1. Field of Invention
The invention relates to an optical projection system and a smooth picture device thereof, and in particular, to an optical projection system capable of smoothing a picture and a smooth picture device thereof.
2. Related Art
Projection systems may be classified, according to projection principles, into three types including liquid crystal display (LCD) projection systems, liquid crystal on silicon (LCOS) projection systems and digital light processing (DLP) projection systems. The DLP projection system advantageously has high luminance, true tone reproducibility, and fast response time. DLP, also by virtue of its noise-free operation and miniature compactness has become the new generation in popular projection systems.
As shown in FIG. 1, a DLP projection system 1 utilizes digital control and the principle of light reflection to converge light beams coming from a light source 11, to pass the converged light beams through a tri-color filter 12, and then to focus the passed light beams onto a digital micro-mirror device (DMD) 14 through a lens assembly 13. Driving electrodes control tilt angles and deflection time periods of a plurality of micro mirrors 141 on the DMD 14 shown in FIG. 2 to switch the light beams to enter a projection lens set 15, which is a turning type lens set including a plurality of lenses and a reflector 151. The reflector 151 turns the light beams to change the light path so that the light beams are amplified by the lens 15 and then projected onto a screen 16.
As shown in FIGS. 1 and 2, each of the micro mirrors 141 of the DMD 14 corresponds to each of the pixels of the displayed picture. Selectively controlling the micro mirror 141 between two different tilt angles enables the light beams to be switched between a first state of entering the projection lens set 15 and a second state of not entering the projection lens set 15.
In order to keep the micro mirror 141 movable, a minor gap exists between two adjacent micro mirrors 141. However, after the enlarging effect of the lenses of the projection lens set 15, the gap is also amplified, thereby influencing the continuity of the picture.
In view of this, it is an important subject of the invention to provide an optical projection system capable of effectively achieving the object of smoothing the picture, and a smooth picture device thereof.